And I'm Audie Cornish. In South Korea today, President Obama consoled a nation in mourning over the victims of a ferry disaster. He also assured South Koreans that the U.S. is committed to support and defend the country in the face of North Korea's threats to test yet another nuclear device. NPR's Anthony Kuhn has been following the president in Seoul and joins us to talk about the trip.

And Anthony, the Korea visit has in some ways been in the shadow of the ferry tragedy. How has President Obama dealt with this?

ANTHONY KUHN, BYLINE: Well, he's had to use great sensitivity in dealing with this issue. He called for a minute of silence ahead of bilateral talks. He presented an American flag that was flying over the White House last week the day the ferry capsized and sank off the southwest coast of Korea.

And he gave a magnolia tree that came from the south lawn of the White House. And this tree was donated to the Danwon High School which is where most of the students came from who were either killed or are still missing on the ship. And here is how President Obama explained about that tree.

PRESIDENT BARACK OBAMA: These magnolia trees have stood for more than a century and they represent, in our country, beauty and with every spring, renewal, the same qualities embodied by all those students.

KUHN: So that tree will now go to the high school as a gift from the president.

CORNISH: As we mentioned, North Korea's threats to test yet another nuclear device, North Korea did not detonate any bombs today. What about the likelihood that a nuclear test is imminent and what did the president have to say about that?

KUHN: Well, in their joint briefing today President Park Geun-hye of South Korea said that in their estimation North Korea is ready to detonate that nuclear bomb at any time, as they have threatened to do. And in his remarks, President Obama says that North Korea's provocative behavior, missile tests and nuclear tests, threatens not just U.S. allies in Asia and U.S. troops there. It's a direct threat to the U.S.

And if the test goes forward, President Obama said there would be a need to talk about tougher sanctions on North Korea. But, as he said, North Korea is already just about the most isolated country in the world and its people are suffering because of its leaders' decisions. And so sanctions may not have a much greater impact on that country.

CORNISH: Finally, Anthony, President Obama has tried to get the U.S.'s two main allies in Asia, South Korea and Japan, to put aside historical enmity. What luck is he having with that?

KUHN: Well, he's had some luck in mediating between South Korea and Japan, whose leaders were not even talking to each other up until about a month ago when he got them together for a trilateral meeting in The Hague. Now, both South Korea and China are still really angry when the Japanese government tries to engage in historical revisionism or tries to make light of its colonization of South Korea, its use of comfort women, in other words, sexual slavery during World War II.

And in his speech today, President Obama said what Japan did during World War II, these were, you know, egregious, serious human rights violations. But the two sides have to own up to them and move on.